In order to reduce the risk of serious bodily injury and damage to cargo and equipment during the loading and unloading of a parked vehicle, it is important that the vehicle be securely held in place at or near the edge of the loading dock. Releasable locking devices for restraining vehicles have been disclosed previously, but the prior art devices have not been capable of belowground storage. They generally have been mounted either on the roadway or on the loading dock wall, where they can be obstacles even when in a stored position.
Thus, the prior art locking devices are subject to being struck by the parking vehicle, particularly if the vehicle has a low clearance. When used in conjunction with certain dock levelers capable of extending down to the ground level, the prior art devices also can present an obstacle to the movement of certain equipment, e.g., the dock leveler and fork lift trucks.
The prior art devices also typically are limited to a specified range of height for the ICC bar of a vehicle for an effective restraint to occur. Other problems with the prior art locking devices include the inability to provide a secure restraint over an acceptable range of horizontal distance between the ICC bar and the loading dock wall. A further disadvantage of the prior art is an inability of the hook to provide angular adaptation to fully engage the ICC bar if the vehicle is not parked at right angles to the loading dock.